Connection for vacuum tubes



Sept. 29, 1925.

e. RESPONDEK.

CONNECTION FOR VACUUM TUBES Filed Nov. 30, 1923 2 Sheets-Sheet l FT A.

K. e :e h. rm r o fo L nw w ee A vR s m H r 0 8 Gb Sept. 29, 1925. 1,555,757

I G. RESPONDEK CONNECTION FOR VACUUM TUBES Filed Nov. 50. 1923 2 Sheets-Sheet 2 lnventdor- Georg Re spondeK;

H is Atdbornea.

Patented Sept. 29, 1925.

UNITED STATES PATENT OFFICE.

GEORG nEsroNnEx, or BERLIN, GERMANY, ASSIGNOR T0 GENERAL ELEo'rEIo com PANY, A CORPORATION on NEW YORK.

CONNECTION FOR VACUUM TUBES.

Application filed November 80, 1923. Serial No. 677,858.

To all whom it may concern:

Be it known that I, Gnonc REsroNDEK, a citizen of Germany, residing at Berlin, Gelmany, have invented certain new and useful Improvements in Connections for Vacuum Tubes, of which the following is a specification.

In telephone or signaling systems having thermionic vacuum tubes connected thereto interruptions may readily occur owing to the fact that one of the tubes may become inoperative; by reason of the burning out of the filament, for example.

The object of my invention is to provide a circuit connection whereby this disadvantage may be overcome and a spare tube automatically connected in the system upon the failure of any one of the tubes.

In carrying my invention into effect, I employ a bridge connection for the different vacuum tubes, which is so arranged that when a tube fails it is automatically replaced wholly or in part by a spare tube. I also provide arrangements in which the number of spare or reserve tubes is less than the total number of tubes in the system and yet a spare tube may be automatically substituted for any of the working tubes of the system. In this case the tubes are arranged in groups in such a way that in case of failure of any tube in the group a reserve tube 'for that group is automatically substituted for the tube which fails.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims; My invention itself, however, both as to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig; 1

shows a lVheatstone bridge connection in which a relay is employed to automatically connect the cathode of a spare tube in circuit when a tube connected in one arm of the bridge fails; Fig. 2 shows a slight modification of the arrangement of Flg. 1; Fig. 3 shows an Anderson brid e connection-in which the substitution is automatically effected without the use of a relay; Fig. 4

shows the system of Fig. 3, connected to a telephone repeater system, and Fig. 5 shows a telephone repeater system comprising a plurality of repeater tubes and a smaller number of spare or reserve tubes.

In the system shown in Fig. 1, A, B, C and D are the junction points of the bridge and 1 is a direct currentsource from which the bridge arms receive current at points A and B. The bridge arms A C, A D and B D are made up of suitably chosen resistances W IV, and W while the fourth arm B C includes the cathode W of a thermionic vacuum tube 2. Resistanoes W and W should preferably' be comparatively large while resistance W should be of the same order of magnitude as the resistance of cathode W,. The cathode W of the substitute tube 3 is connected between the junction points 0 D of the bridge in series .with the winding 4 of a relay having an armature 5. When the relay is'not actuated the armature 5 is in the full line position shown in the drawing. The bridge arms are so proportioned that normally no current flows from C to D. If now, for example, cathode W burns out the balance of the bridge is upset and current flows from C to D through the winding 4: and through the cathode W, of tube 3. The armature 5 is attracted to the dotted line position shown on the drawing so that the arm W is replaced by the arm W The current relations of the different arms of the bridge will remain the same however as they were before the change was made. i

In the arrangement shown in Fig. 2 the bridge is fed by an alternating current source 6. In order to avoid losses in this case the arms IV, and IV of the bridge may be advantageously replaced by the condensers C, and C The heating current may also in this case, if desired, be supplied to the cathodes of the tubes by transformers. In this case also the relay is so connected that when actuated the arm W is replaced by an arm 1V5, and the condenser C is short circuited. The same modification might be employed with the arrangement of Fig. 1, in which case the resistance \V, would be short circuited. If we assume that C, or

W. has a large complex, that is, a large ohmic resistance, the conductivity of the bridge will vary but little with the two systems of connection as will be indicated by the following analysis Let W=the resistance of the bridge then the conductivity of the bridge When W =W this becomes K and is In the arrangements thus far described the same current relations before and after the reserve tube has been put in operation are maintained only by the use of a relay. In the arrangement shownin Fig. 3 the desired result is obtained solely by an Anderson bridge connection which operates by simple current division Without the use of any switching means. In this case as before the bridge A B C D is fed by a battery 1 at the points C D. The arm A D includes the cathode R, of the tube 7, while the cathode R of the reserve tube 8 is included in the divisional branch A E of the bridge A B. For the currentless state of the divisional branch there exists between the different resistance the following relation:

The resistance of the arm A D is now so chosen that The remaining resistances of equation may now be so chosen that the current supplied to tube 8 after the burning out of the cathode of tube 7 is the same as that supplied to the cathode of tube 7. The case where the divisional branch E B is eurrentless after the burning out of the cathode of tube 7 may be expressed by the following equa- If now in consideration of these conditions the value of the resistance W is chosen in equation (1) then when the filament R, burns out the same heating current will flow through R, as flowed through R before it burned out. A strict fulfillment of equation (3) is not necessary. For example, the resistances WV, and W, may be so chosen that the shunt current flowing in the branch 13 1 1 1 wwwmfwrwm-wzlwz'wz-wwi If now W is chosen e ual to W and \V the resistance of the bridge after the connections are changed the difference between the conductivities of the bridge under the two conditions is of the bridge does not produce any disturbin action.

11 the arrangement of Fig. 4 I have indicated the application of the system of Fig. 3 tea telephone repeater having an incoming line 9 and an outgoing line 10 connected thereto. If the filament of tube 7 burns out the filament of tube 8 is immediately energized. The grids 11 and anodes 12 of the two tubes are connected to. each other so that the only change necessary to substitute one tube for the other is to transfer the filament heating current from one tube to the other. Obviously the systems shown in Figs. 1 and 2 can be applied to a telephone repeater in the same manner.

In Fig. 5 I have indicated a system comprising a plurality of telephone lines showing the manner in which a smaller number of substitute tubes can be arranged for substitution in any one of the lines. Four such lines may be used in the system illustrated but for convenience and simplicity of illustration only one line is shown having incoming conductors F and outgoing conductors F. Two substitute. tubes 13 and I l having cathodes R, and R are shown in the drawing.

The manner of operation of the system illustrated is as follows: If the filament of the operating tube, which is not shown in the drawing, burns out the switch. 15 is closed by means of a suitable relay device. This makes contact at 16 and closes a circuit from earth at 17 through switch 18, rotary magnet 19, switch 20 to earth at 21. In this circuit the rotary magnet 19 is alternately energized and deenergized. The function of the rotary magnet 19 is to turn the switching arms 22 to 26, inclusive, of the selective switching device 27 over the stationary contacts 28, 29. 30 and 31. When the switching arm 26 strikes the stationary contact 28 the circuit 15, 16, 32, 33, 26, 28, 34, 35, 36, is completed. In this circuit relay 32 will function and open switch 18 causing the rotary magnet 19 and the selective switch 27 to stand still. Relay 33 is also energized and serves to close switch 37, thus short circuiting the winding of relay 32, thereby preventing the line from being occupied by another selective device. Relay 35 closes contact 38 and thereby closes the circuit of battery 39 for the substitute tube 13. If now the substitute tube should burn out current will flow over the divisional branch A G of the bridge A B in which relay 40 is connected. This opens contact 34 breaking the circuit through relay 33. The rotary magnet then starts to move and turns the switch arms on to the next contact which is connected to an operative tube.

It will be notedthat all of the modifications of my invention illustrated have the advantage that the cathode of the substituted tube when not connected up for operation is entirely without current.

What I claim as new and desire to secure by Letters Patent of the United States, is z:-

1. The combination in a system comprising a thermionic vacuum tube of a bridge, a pair of tubes having their cathodes associated with said bridge in such a way that normally current is supplied through the bridge to the cathode of one tube only, and means. for automatically supplying current to the cathode of the other tube when the circuit of the cathode of the first tube is broken.

the cathode for supplying current to the cathodeof another tube.

4. The .combination in a system comprising a bridge and a thermionic vacuum tube of a pair of, tubes having their anodes and grids connected together respectively and -their cathodes included in said bridge,

means whereby current is normally supplied to the cathode of one tube only and means responsive to an unbalancing of the bridge in a system comprisvacuum tubes having their grids connected together to an incoming line and their anodes connected together to an outgoing line, means for supplying current to the cathode of one tube only and means directly responsive to the interruption of current through the cathode of one tube for supplying current to the cathode of the other tube.

The combination in as stem comprising a bridge and a thermionic vacuum tube of a pair of vacuum tubes having their grids connected togetherto an incoming line, their anodes connected together to an outgoin line and their. cathodes includedin said ridge, means for supplying current to the cathode of one tube only and means responsive to an unbalancing of the bridge for su plying current to the cathode of the other tu e.

8. The combination in a system comprising-a bridge and a thermionic vacuum tube of a pair of vacuum tubes having their grids connected together to an incoming line, their anodes connected together to an outgoin line and their cathodes included in sai bridge, means for supplying current to the cathode of one tube only and means responsive to an interruption of thecircuit of one cathode for supplying current to the cathode of the other tube.

In witness whereof, .I have hereunto set my hand this 12th day of November, 1923.

GEORG RESPONDEK. 

